1. Field of the Invention
This invention generally relates to check valves and more particularly to check valves having a pair of pivotal valve members for controlling the flow of fluids therethrough.
2. Description of the Prior Art
While the invention has features that make it applicable for many purposes in various fields, the present disclosure is directed particularly to the passing of heated, compressed air through ducts to start jet aircraft engines. One method of starting a jet aircraft engine consists of furnishing substantial volumes of air at relatively high pressure and temperature to a turbine starter which brings the jet engine up to the speed necessary for its ignition. The air is conventionally supplied to the turbine starter through a duct system having an input nipple accessible from the exterior of the engine cowling and through a check valve for preventing the loss of fluid pressure from the duct system.
One of the most serious problems confronting the check valves used in such systems is that they are subjected to relatively high temperatures and pressures in moving large volumes of heated air, wherein the strength of the valve members is critical and yet their weight must be minimal. Usually such valve members are formed from thin metal sheets and thus they are easily warped or otherwise distorted by the heated compressed air, resulting in failure of the check valve after a short period of use.